Method of harvesting timber trees in a jungle and a machine for performing said method

ABSTRACT

A method of harvesting standing trees in a jungle comprising bringing a crawler crane, preferably a hydraulic crawler crane, with a boom ( 14 ) to a block of jungle, securing the tree to be harvested to a sling in the boom, cutting the base of the tree, removing the cut tree using the boom, laying the cut tree on the ground, and cutting the crown of the cut tree. In another aspect the crown of the tree is cut first and removed by means of a sling on the boom of the crane. The crane is used to remove the crownless tree, or the crownless tree is cut at the base and allowed to fall. Main roads, spur roads, and snig tracks are constructed in the logging area. Alternatively, another method of harvesting cut trees in a jungle includes bringing a crawler ( 20 ) with a boom structure ( 26 ) to a block ( 102 ) of jungle, securing the harvested timber ( 70 ) to a winching cable ( 40 ) on the boom structure ( 26 ), stabilizing the crawler ( 20 ), and snigging the harvested timber ( 70 ) toward the crawler so that the harvested timber is at an inclined angle with respect to the ground. A forest harvesting machine comprising a crawler ( 20 ) with a boom structure ( 26 ), a winch, and a foldable arm structure ( 30 ) is also disclosed, having grasping claws ( 34 ) pivotally mounted along the boom structure ( 26 ), wherein during the snigging of harvested timber ( 70 ), the foldable arm structure ( 30 ) is used to stabilize the crawler ( 20 ).

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional of, and claims the benefit of,application Ser. No. 09/605,151, filed Jun. 28, 2000, which status ispending, which application is hereby incorporated herein in its entiretyby reference.

FIELD OF THE INVENTION

The present invention relates to a method of harvesting timber trees ina jungle, and more particularly relates to a method of snigging orretracting fallen timber trees in a jungle, and machine used in themethod to snig the harvested timber trees to a cleared site in thejungle.

BACKGROUND OF THE INVENTION

It is known in the art relating to methods of forest harvesting, andparticularly the harvesting of timber trees in tropical jungles, thatthe jungle ground is cleared of vegetation to allow the passage oflorries and cranes. The trees selected for harvesting are cut at theirbase, and allowed to fall generally in a predetermined direction. Thefall of the trees damages all growth, including smaller trees and youngsaplings on the ground. The branches of the fallen tree are then cutoff, and the timber trunk is snigged, or skidded, to a cleared area ofthe jungle for further cutting or loading into transport vehicles. Thesnigging or pulling of the trees along the ground further damages thevegetation on the ground. To enable lorries and cranes to reach thefallen tree, all vegetation on the path of travel for the lorries andcranes is removed. This causes further destruction of the vegetation orjungle cover. It is not uncommon, therefore, to find entire blocks ofjungle laid barren in the harvesting and transporting of timber trees intropical jungles. The known methods of transferring timber trees intropical jungles typically result in the destruction of more than 60% ofthe jungle cover, a level of destruction that is totally undesirable.

Because of the destruction of young trees, saplings, and vegetation, thejungle cannot regenerate itself within a reasonable time. Under presentpractice, it takes more than 100 years before the re-harvesting of newtimber trees can be considered in many tropical jungle areas. U.S. Pat.No. 4,114,666 to L. O. Bruum discloses a method of forest harvesting,and a machine for performing said method. The method and machinedisclosed, though useful for harvesting timber trees in temperate orcultured forests, are not suitable for harvesting larger sized andbranched tropical timber trees.

Another method of harvesting timber trees in tropical countries involvesthe use of helicopters. Helicopters are used to cut the crown of thetree, and to lift the cut tree to a logging yard. Although this methodreduces damage to jungle cover to below 10%, it is not yetcost-effective or practical to continue use in harvesting an entirejungle area because the profit margins are greatly reduced, making themethod economically unattractive.

Thus, there is a need for harvesters of tropical timber in tropicaljungles to comply with the criteria laid down by the Forest StewardshipCouncil's Principles and Criteria (P&C). More particularly, there is aneed for an effective method of harvesting tropical timber trees, and tomanage the manner in which the vehicles are used in snigging the cuttimber trees within the logging area such that there is minimumdestruction of the uncut timber trees and the undergrowth.

SUMMARY OF INVENTION

The present invention discloses a method of harvesting standing trees ina jungle that includes bringing a crawler crane with a boom to a blockof jungle, securing the tree to be harvested to a sling in the boom,cutting the base of the tree, removing the cut tree using the boom,laying the cut tree on the ground, and cutting off the crown of the cuttree.

In another aspect of the invention, the method of harvesting standingtrees in a jungle includes bringing a crawler crane with a boom to ablock of jungle, securing the crown of a tree to be harvested to a slingin the boom, raising an operator to the crown portion of the tree,cutting the crown portion of the tree, removing the operator from thetree, removing the crown of the tree, and cutting the crownless tree atthe base of the tree.

The crawler crane is preferably a hydraulic crawler crane. To enable thecrawler crane to travel in the jungle, a main road is constructed acrossa predetermined area of the jungle, a spur road is constructed leadingfrom the main road to a log landing area for a given sub-block of thejungle, and a plurality of snig tracks which extend radially from thelog landing area are constructed in each sub-block of the jungle. In yetanother aspect, a main road is constructed across a predetermined areaof the jungle, and a plurality of spaced and parallel snig tracks areconstructed extending from the main road, the distance between adjacentsnig tracks being substantially equivalent to two to three times thelength of the boom of the crane.

To attach the sling of the boom to the crown of the tree, and to cut thecrown portion of a standing tree to be harvested, an operator is liftedto the crown portion of the tree in a steel cabin secured to the boom ofthe crane. The operator's cabin of the crawler crane is fortified bymeans of a metal cage. The sides of the crane boom are enveloped bymetal plate sidings to avoid or reduce the likelihood of entanglingfoliage within the lattice of the boom where the crane is used. The boomof the crawler crane is constructed to swing 360° in a horizontal circleabout the crawler, and to be raised up to 90° in the vertical axis.

Typically the area of the jungle to be harvested when the crawler craneis positioned in the jungle is a circular area covered by the length ofthe boom of the crane, usually 60 meters. However this circular area ofthe trees to be harvested can be extended by the use of connectorslings. Typically the circular area can be extended by an additionalradial length of 16 meters.

Alternatively, and in another method of harvesting cut trees in ajungle, a crawler with a boom structure is brought to a predeterminedblock of the jungle, the harvested timber is secured to a winching cableon the boom structure, the crawler is stabilized, and the harvestedtimber is secured toward the crawler so that the harvested timber ismoved in an inclined angle in relation to the ground. The winching cableis brought to the timber by securing it to an auxiliary winch cable ofan auxiliary winch on the crawler, and retracting the auxiliary winchcable around an obstacle. The height of the boom structure issubstantially more than 5 meters above ground so that the harvestedtimber is snigged in an inclined angle in relation to the ground toreduce obstruction and damages.

Another method of harvesting cut trees in a jungle includes constructinga main road across a predetermined area of jungle. A plurality of skidtrails are then constructed leading from the main road, where thedistance between adjacent skid trails is in the range of 200 to 300meters.

A forest harvesting machine for practicing the above-described methodscomprises a crawler with a boom structure, a winch assembly, and afoldable arm structure with grasping claws pivotally mounted along theboom structure. The foldable arm structure is used to stabilize thecrawler during the snigging of harvested timber, and is operated by ahydraulic system. The crawler is stabilized on the ground by thefoldable arm structure. A timber may be held on the ground by thegrasping claws of the foldable arm structure for stabilizing thecrawler. The crawler further includes an auxiliary winch assembly.

In another embodiment, the crawler has a boom structure mountedpivotally to a backhoe arm. A claw is secured to one end of the boomstructure, and a roller guide assembly is secured to the other end ofthe boom structure. The crawler further includes an auxiliary winchassembly.

Further advantages and characteristics of the invention are given belowin the description of the method of jungle harvesting of timber trees ina tropical jungle. Also described are the layout pattern of tracks, andan apparatus used in relation thereto, with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a crane operators cabin shield.

FIG. 2 shows a crane with steel plate sidings on the boom of the crane.

FIG. 3 is an isometric view of the steel plate sidings of the boom ofthe crane of FIG. 2.

FIG. 4 shows a worker pruning the crown of a timber tree to beharvested.

FIG. 5 is a perspective view of a first embodiment of a machine used tosnig the cut timber trees.

FIG. 6 shows the detail of the winch assembly to which cables aresecured to the boom.

FIG. 7 is a perspective view of a second embodiment of a machine used tosnig cut timber trees.

FIG. 8 shows the pull out and haul back of the main winch cable.

FIG. 9 is an illustration of a crane lifting a cut tree.

FIG. 10 is another illustration of a crane lifting a cut tree.

FIG. 11 is an illustration of a crane skidding a cut timber trunk.

FIG. 12 is an illustration of a crane lifting a cut timber trunk.

FIG. 13 is a schematic plan view of a harvested area where the timbertrees are felled in a herringbone pattern.

FIG. 14 shows the forward end of a cut timber tree being cut intofrustocone.

FIG. 15 shows a manner in which a cut timber tree may be moved in whichthe cut tree is inclined in order to go over obstacles along the path oftravel.

FIG. 16 shows a timber tree being conveyed on a fabricated steel sledge.

FIG. 17 is a perspective view of the sledge of FIG. 16.

FIG. 18 shows a manner in which a cut timber tree may be moved on asledge in which the tree is inclined in order to go over obstacles alongthe travel path.

FIG. 19 shows logs being skidded along skid tracks using a hydraulicexcavator.

FIG. 20 is a side view of a crane operating in a mountainous or hillyforest.

FIG. 21 is a top plan view of a road track pattern for a crane in ablock of a logging area.

FIG. 22 is a top plan view of a first path of the crane moving within asub-block in the logging area.

FIG. 23 is a top plan view of a second path of the crane moving within asub-block in a logging area.

FIG. 24 shows the snigging of cut timber trees on a sloped terrain.

DETAILED DESCRIPTION OF THE INVENTION

Before commencing the harvesting operation, a pre-harvest inventory isconducted appropriate to the scale of the planned block usingpredetermined strip lines to gather the species composition,identification of trees to be cut, diameter, classification, and heightof merchantable trees, and to forecast the yield per hectare. The treesto be harvested are marked at the same time. The tree marking isimportant and necessary in order to guide the chainsaw operators tothose trees to be cut, and to indicate an arrow pointing in thedirection of the fall for the respective trees to ensure and minimizedamage to residual trees and young saplings during extraction of the cuttrees.

According to a first embodiment of the invention, a hydraulic crawlercrane, for example a model 1H1-CCH1000 crane, with a lifting capacity ofsubstantially 100 metric tons is used for the purposes of lifting,skidding, and yarding of the timber, or cut trees. The terms “skidding”and “snigging” are used interchangeably, it being known to those ofskill in the art that these terms describe the dragging or movement ofharvested timber across a surface for the purpose of collecting cuttrees. The boom of the crane in the preferred embodiment is at least 60meters or 197 feet in length, and is capable of swinging in both thevertical and horizontal planes. The operator's cabin is fortified. Ametallic web 10 is enclosed around the operator's control station in thecrane (FIG. 1).

In order to prevent the branches of the crown of the tree, and othervegetation from getting entangled with steel frame lattice 12 of theboom 14, the boom of the crane is enveloped using a desired number ofsteel plate sidings 16 (FIGS. 2 and 3). Other rigid plates can also beused for the sidings. To enable an operator to cut the crown of the treeto be harvested, a steel cabin enclosure 18 is provided (FIG. 4). Thesteel cabin enclosure 18 is designed to accommodate at least one person,and to be lifted to the crown region of the tree by the boom of thecrane.

Further, in order to allow the travel of the crawler crane in the swampyor soft ground of the jungle, suitable crane track slippers areprovided. These crane track slippers are preferably constructed ofhardwood timber slabs tied together to form a planar slab assembly, orassemblies, as needed. The slab assemblies are reused as trackconstruction progresses. In the known methods of constructing tracks forlorries, yound trees are often cut and laid on the ground to form a firmfoundation for the lorries to travel. This cutting of young trees toconstruct the track further destroys the jungle vegetation, which is anundesirable practice.

The hydraulic crawler crane can be used to skid or snig cut timbertrees. However, it is necessary to stabilize the crawler crane beforesnigging the timber tree. This is done by securing a stabilizer memberto the boom 14 of the crane, or adopting other methods known in the artsuch as the provision of a backhoe 52 on the crane. Where the boom 14 isconstructed as a steel frame lattice, the crawler crane may not bestrong enough to snig heavy timber trees. However, the crawler crane canbe used to snig timber trees which are of smaller size or which arelight. Thus the hydraulic crawler crane can also be used to snig cuttimber trees provided the crawler is stabilized using a stabilizermember (not illustrated), and the weight of the timber to be snigged iswithin the safety limit of the steel lattice structure framework of theboom 14.

In a second embodiment, the general construction of a crawler 20 isshown in FIG. 5. The crawler 20 includes a revolving upper structure 22rotatably mounted on an undercarriage 24. The revolving upper structure22 has a front end from which a boom structure 26 is connected. The boomstructure 26 is pivotally moveable in a vertical plane with the help ofhydraulic cylinders. A roller guide 28 is provided at the top end of theboom structure 26 for winching purposes. (FIG. 5)

The crawler also includes a foldable arm structure 30 (FIG. 5). The rearend of the foldable arm structure 30 is pivotally connected to the boomstructure 26 and includes a hydraulic cylinder to rotatably move the armstructure 30. The other end of the arm structure 30 is connected to agripper 32. The gripper 32 includes a pair of claws 34, which areswingable toward and away from each other. The claws 34 are operatedwith the help of hydraulic cylinders mounted on the arm structure 30.The height of the boom structure 26 of the crawler 20 should besubstantially greater than five meters. In the preferred embodiment, theheight of the boom structure is substantially 14 meters, or 46 feet,from the track shoe 36 to the top end of the boom structure 26, whereasthe arm structure 30 is preferably about 6.5 meters long. The boomstructure 26 can also be an extendable type, whereby the extension isexecuted by a suitable hydraulic system (not illustrated).

The crawler 20 is provided with a main winch assembly 38. The winchassembly 38 comprises, in a preferred embodiment, a 122 meters, or 400foot, long winching cable 40. The winching cable 40 is preferably 2.5cm, or 1 inch, in diameter, and is rolled on a roller 42 which ismounted on the revolving upper structure 22 shown in FIG. 6.

A cabin 44, from which an operator operates the crawler is placed on therevolving upper structure 22. The cabin 44 also contains variouscontrols to operate the crawler 20 efficiently. A portion of the cabin44 is covered with reinforced steel bars 46 for safety purposes (FIGS.5, 7).

An auxiliary winch 48 is also provided as a part of the crawler 20 (FIG.7). The auxiliary winch 48 includes an auxiliary winch cable 50, whichis of smaller diameter compared to the winching cable 40. As the weightof the winching cable 40 is relatively large, the auxiliary winch cable50 is used to pull the winching cable 40 out to the desired felled tree(FIG. 8).

In a third embodiment, the crawler 20 can also be constructed in such away that the boom structure 26 is pivotally joined to an existing armstructure of a backhoe 52, as shown in FIG. 7. In this case, a gripper32 is attached to one end of the boom structure 26, whereas he other endis provided with a roller guide 28 used for winching purposes. However,the working mechanism for this embodiment is the same as the seconddescribed embodiment.

In a fourth embodiment (not illustrated), the crawler 20 can also beconstructed in such a manner that an independent boom structure 54 ispivotally mounted on an existing undercarriage 24 of the backhoe 52. Thearm structure 30 of the backhoe 52 is still used as a stabilizer. Agripper 32 is attached to one end of the arm structure 30, and a rollerguide 28 is provided at the terminal end portion of the boom structure26. In other words there will be two, separate independent structuresmounted on the crawler 20.

Referring now to the first embodiment, a hydraulic crawler crane with adesigned load capacity of substantially 100 metric tons and with boomlength of 60 meters is used. For a given sub-block of jungle to beharvested, a logging road 56 and a spur road or roads 58 are constructedin stages as the logging progresses deeper into the jungle. Trees andvegetation along the path of the proposed logging road are removed usingthe method of harvesting trees to be described herein. Other vegetationalong the proposed logging road is removed using conventional methodsbut ensuring areas beyond the boundaries of the logging road are notdamaged. The hydraulic crawler crane now enters the logging road 56. Acrane hook 60 is secured to the tree to be cut, preferably at the crownregion of the tree by an operator who is hoisted to the crown of thetree by the crane. The operator is accommodated within a protectivecabin. A chainsaw operator then will cut the tree at the root region.After the tree is cut, the crane will lift the cut tree together withthe uncut crown and deposit the tree at the log landing area (FIGS. 9and 10). At the log-landing area, an operator will remove the unwantedfoliage and branches of the cut tree. He will also cut the timber to thedesired length(s). This process is repeated all over the area covered bythe boom of the crane, with a radial working radius/length ofsubstantially 61 meters.

As shown in FIG. 4, in another aspect of the invention, before fallingthe timber trees to be harvested, the crowns of the tree are cut. Thechainsaw operator is lifted to the crown region of the tree by the cranein a steel cabin enclosure 18. Rigging cables 62 are secured to thebranches at the crown of the tree. The crown is cut at its basal portionand is thereafter lifted by the boom of the crane and deposited at aclear area where the branches are further pruned. The purpose of cuttingthe tree crowns on standing trees is an important factor to reducedamage on residual trees and young regeneration foliage. Moreover, withthis method the maximum load to be carried by the crane is also reducedby the harvesting of the tree in two stages: the first stage involvingthe removal of the crown of the tree, and the second stage involving theremoval of the trunk of the tree.

In another aspect of the invention, a connector sling cable, or cables,64 are used to secure the crown or the trunk of a cut tree to thepre-existing sling cable of the boom of the crane. By the use of theconnector sling cable(s) 64, the working radius of the crane can befurther extended (FIGS. 11 and 12). At areas beyond the radius of 61meters from the position of the crawler crane, the trees are felled bycutting the tree at the base of the tree and allowing the tree to fallin an already harvested area of the jungle. Then slings are secured tothe fallen tree which is then snigged to the log-landing area by thecrawler crane.

In the second, third, and fourth embodiments described herein, a reasonfor using the winch assembly 38 is to restrict the movement of thecrawler 20 from going inside the demarcated logging area. The crawler 20will remain only on the main road 66 and skid trails 68, and snig thetimber 70 out using the winch assembly 38. This is to reduce thepercentage of forest area from being destroyed during harvesting.

The method of snigging cut timber trees using the crawler 20 in thesecond, third, and fourth embodiments is now described. A tree feller72, a chainsaw operator, will be trained for the directional felling oftimber 70. This will be done by aligning the pattern and the sequence ofthe cutting of the tree(s) 70 in a “herringbone” pattern to the skidtrails 68 and avoiding the need for an excavator to align the cut timber70 tree on the ground before winching (FIG. 13). This practice allowsefficient and minimum impact during the process of winching the timber70 from the felled area to the skid trails 68. After harvesting thetrees, the tree feller 72 will cut the timber head or timber end to forma cone or frustocone (FIG. 14). This is to allow the timber 70 to bewinched smoothly to reduce friction during the winching operation (FIG.15).

A sledge 74 can also be used to convey the timber 70 during the winchingprocess (FIG. 16). The sledge 74 has a bow portion 76 and a base portion78. A substantially “C”-shaped hook 80 is provided at the terminal endportion of the bow portion 76. The C-shaped hook functions as a guide sothat the sledge 74 moves in the direction of the winching cable 40 (FIG.17). The base portion 78 is preferably curved like the base of a boat,and includes a plurality of projecting spikes 82. The spikes grip thetimber and prevent it from sliding backwards off of the base portion 78during the winching process (FIG. 17). A sling chain 84 is also providedon the base portion 76 to further secure the timber 70 on the sledge 74.The sledge 74 is preferably boat shaped in cross-section. At theterminal end of the winching cable 40, a substantially “S”-shaped hook86 is provided (FIG. 17). The function of the S-shaped hook 86 will bedescribed later.

Before winching the timber 70, another timber 88, which has already beenharvested earlier, is used as a stabilizer. The stabilizing timber 88 isgripped between the claws 34 of the gripper 32 and placed horizontallyon the ground as shown in FIG. 5. As mentioned earlier, the crawler 20includes the auxiliary winch 48, which is used to pull out the winchingcable 40 to a point near the harvested timber 70. The winching cable 40is pulled out by using the auxiliary winch cable 50 and a pulley 90,which is tied around a tree near the timber 70 (FIG. 10). After riggingthe timber 70, which is to be winched out, a rigger 92 will communicatewith the operator of the modified hydraulic excavator to startpulling/winching the timber 70 away from the cutting area.

When the steel sledge 74 is used, the timber 70 is placed on the baseportion 78 of the sledge 74. The projecting steel spikes 82 will gripthe timber 70 when it is laid on the sledge. The sling chain 84 is thensecurely tied around the timber 70 by means of bolt and nut or by anyother means known to the art. Thereafter, the winching cable 40 is alsotied around the timber 70 by using the S-shaped hook 86 shown in FIG.18. When the winching cable 40 is retracted, the grip around the timber70 will increase. This will further secure the timber 70 in its positionon the sledge 74.

The winch cable 40 is rigged to the harvested timber 70 in a manner suchthat the harvested timber is held at an inclined angle with respect tothe ground. This enables the harvested timber being snigged to be movedover any obstacles lying along the path of travel (FIG. 7). This methodalso reduces the damage to the ground when the harvested tree is pulledalong the ground.

All winched timber 70 will be stacked at both sides of the skid trails68. Thereafter, another excavator, for example a PC-100 model excavator,will skid the timber 70 out to a main road 66 (FIG. 12). In the second,third, and fourth embodiments, the foldable arm structure 30 is used tostabilize the modified hydraulic excavator. However, it is also possiblethat the arm structure 30 can be used to lift and load the timber 70onto a truck.

In the harvesting of timber in hilly or mountainous areas, roads arefirst constructed in alignment with the terrain of the jungle. The roadsare constructed using hydraulic excavators on the top ridges and theside ridges in these hilly forest areas. The road will have a maximumwidth of 7.32 meters to accommodate hydraulic crawler cranes and loggingtrucks during the logging operation. Hydraulic excavators are preferredas compared to the use of hydraulic tractors because the use ofhydraulic tractors causes heavy damage to the forest cover. In the knownmethods of road construction in the jungle, bulldozers or tractors areused. Excavation and road formation by the use of tractors or bulldozersresults in a great deal of excess earth, which has to be disposed orcleared from the site of the would-be road. This excess earth is justpushed down the slopes. The bulldozer cannot be used to compact theexcess earth. The disposal of the excess earth onto the slopes resultsin serious soil erosion, particularly in enveloping the youngregeneration foliage and in heavy damage to the residual trees.

By using a crawler excavator the excess earth is constructed intoembankments or earth bunds, formed to be 1.5 meter wide by 1.0 meterhigh, on the edge of the road or carriageway. The embankments or bundsare compactable and may be tamped using the bottom side of theexcavator's bucket. Very little of the carriageway or the compacted bundis washed away during heavy rainfall. Heavy compaction is also reducedby the use of hydraulic crawler crane excavators. A hydraulic crawlercrane with a skidding distance in the range of 91 meters to 122 meters,300 feet to 400 feet, from the center of rotation is used. The activityof log lifting is properly planned based on the laws of physics wherethe maximum load capacity is a function of the working radius of theboom. Normally the maximum working radius is up to 61 meters, 200 feet,to be within its maximum design lifting loads. However, it is possibleto skid logs from a 122 meters, 400 feet, working radius before lifting(FIG. 20). Where necessary, connector sling cables are used to lift thecut logs. Bigger capacity crawler cranes can be used to harvest timberof heavier weights. In hilly forests, the area of each sub block is 15acres.

Referring to FIG. 21, a layout of the road network of a block of about510 acres of virgin jungle for the first embodiment of the invention isshown. The large block is demarcated by means of smaller imaginarysquare sub-blocks of 10 acres each. A main road 94 is laid across themid-way of the large block 96. The timber trees along this proposed mainroad 94 are harvested according to the method described hereinabove, oras known in the art. The width of the main road is substantially 7.32meters. From the main road 94 a pair of parallel logging roads 56 areconstructed dividing the large block into six blocks. Each of theseblocks is further subdivided into a square block of 10 acres.

In each sub-block a spur road 58 is cut across the block at a rightangle to the logging road 56. The spur road 58 is cut to terminate atthe mid-point of the sub-block. The mid-point region of each sub-blockserves as a log-landing yard. From the log landing yard a plurality ofradially extending snig tracks 98 are constructed. Where the crane boom14 is 61 meters, 200 feet, in length, the snig tracks 98 can extend fromabout 61 to 76 meters, 200 feet to 250 feet, of the border of thesub-block of the logging area (FIG. 22). Thus by this layout of the spurmain road, spur road and snig tracks, it is possible for the crane boom,if necessary, and with the further use of connector sling cables 100, toreach every tree within harvesting sub-block. The total area damaged bythe use of this method of harvesting is below 10% as compared to morethan 60% in prior art methods. Table 1 below shows the usage of the areain a block of 510 acres utilizing the above described pattern.

TABLE 1 Roads and Snig Tracks Design Block 7 Area: 1,999,200 m² (510.00acres) Length Width Area M (Chain) M (Ft) M² (Acres) Road Rd 1 1009.8(51) 7.2 (24) 7270.56 (1.856) Rd 1-1 891 (45) 7.2 (24) 6415.20 (1.637)Rd 1-2 910.8 (46) 7.2 (24) 6557.76 (1.674) Rd 1-3 910.8 (46) 7.2 (24)6557.76 (1.674) Rd 1-4 891 (45) 7.2 (24) 6415.20 (1.637) Spur Roads Sr-1198 (10) 7.2 (24) 1425.6 (0.364) Sr-2 198 (10) 7.2 (24) 1425.6 (0.364)Sr-3 198 (10) 7.2 (24) 1425.6 (0.364) Sr-4 198 (10) 7.2 (24) 1425.6(0.364) Sr-5 198 (10) 7.2 (24) 1425.6 (0.364) Sr-6 198 (10) 7.2 (24)1425.6 (0.364) Sr-7 198 (10) 7.2 (24) 1425.6 (0.364) Sr-8 198 (10) 7.2(24) 1425.6 (0.364) Sr-9 198 (10) 7.2 (24) 1425.6 (0.364) Sr-10 198 (10)7.2 (24) 1425.6 (0.364) Sr-11 198 (10) 7.2 (24) 1425.6 (0.364) Sr-12 198(10) 7.2 (24) 1425.6 (0.364) Sr-13 198 (10) 7.2 (24) 1425.6 (0.364)Sr-14 198 (10) 7.2 (24) 1425.6 (0.364) Sr-15 198 (10) 7.2 (24) 1425.6(0.364) Sr-16 198 (10) 7.2 (24) 1425.6 (0.364) Sr-17 198 (10) 7.2 (24)1425.6 (0.364) Sr-18 198 (10) 7.2 (24) 1425.6 (0.364) Sr-19 198 (10) 7.2(24) 1425.6 (0.364) Sr-20 198 (10) 7.2 (24) 1425.6 (0.364) Log Landings60 Landings (Area = 1920.99 m² (0.49 Acres) 115259.76 (29.400) perlanding) Grand Total 8573.4 m 176,988.24 m² (433 Chains) (45.158 Acres)Percentage = 8.85%

After the tree harvesting in one sub-block is complete, the crawlercrane moves to the adjoining sub-block, where the harvesting process isrepeated. Conventional transport lorries remove the harvested logs fromthe logging yard.

Another layout pattern of the main road 94 and the snig tracks 98 isshown in FIG. 16. It will be seen that the snig tracks 98 are laidparallel to each other and extend from the main road 94. The distancebetween two adjacent snig tracks 98 is substantially 182 meters, or 600feet. By adopting this layout configuration of the main road 94 and thesnig tracks 98 it is possible for the crawler crane with a 50 meter, 165foot, boom to reach every tree between two adjacent snig tracks 98.Table 2 shows the usage area in a block of 216.74 hectares.

TABLE 2 Roads and Snig Tracks Design Block No. 42 Area: 2099687.8 m²(535.58 acres) Length Width Area M (Chain) M (Ft) M² (Acres) Road Rd A1207.8 (61) 7.2 (24) 8696.16 (2.220) Rd B 1643.4 (83) 7.2 (24) 11832.48(3.020) Rd C 415.8 (21) 7.2 (24) 2993.76 (0.764) Snig Tracks ST-1 336.6(17) 7.2 (24) 2423.52 (0.619) ST-2 237.6 (12) 7.2 (24) 1710.72 (0.437)ST-3 138.6 (7) 7.2 (24) 997.92 (0.255) ST-4 1207.8 (61) 7.2 (24) 8696.16(2.220) ST-5 1366.2 (69) 7.2 (24) 9836.64 (2.511) ST-6 1386 (70) 7.2(24) 9979.2 (2.547) ST-7 1306.8 (66) 7.2 (24) 9468.96 (2.402) ST-81227.6 (62) 7.2 (24) 8838.72 (2.256) ST-9 1148.4 (58) 7.2 (24) 8268.48(2.110) ST-10 1069.2 (54) 7.2 (24) 7698.24 (1.965) ST-11 990 (50) 7.2(24) 7128 (1.819) ST-12 574.2 (29) 7.2 (24) 4134.24 (1.055) ST-13 831.6(42) 7.2 (24) 5987.52 (1.528) ST-14 732.6 (37) 7.2 (24) 5274.72 (1.346)ST-15 653.4 (33) 7.2 (24) 4704.48 (1.201) ST-16 475.2 (24) 7.2 (24) 3420(0.873) ST-17 277.2 (14) 7.2 (24) 1995.84 (0.509) Total 17,226 m121845.76 m² (870 Chains) (31.657 Acres) Percentage = 0.059%

Referring now to the second, third and fourth embodiments, theanticipated amount of forest damage due to the construction of the mainroads and the skid trails 68 utilizing the modified hydraulic excavatorin an actual study is tabulated below. A block 102 of the forest is usedto compute the damages. The block includes, a main road 66 and ten skidtrails 68 on either side of the main road. The total area of the mainroad 66 and the skid trails 68 constructed is 5.095 hectares out of atotal block area of 203.20 hectares, giving a percentage of 2.5% ofdestroyed area.

The area of damage caused by the snigging of harvested timber 70 isestimated by multiplying a factor of 0.0078 hectares for every logcorridor during the winching. If a total of 3,510 trees are winched, atotal area of 24,696 hectares is damaged, giving a percentage of 12.15%out of the area of block 102 of 203.20 hectares. The total area damageddue to harvesting of timber is therefore 29.095 hectares out of theblock of 203.20 hectares, comprising 14.66% of the area harvested.

MAIN ROAD AND SKID TRAILS (COMPARTMENT NO. 41) AREA: 203.20 Hectares(HAS) LENGTH WIDTH AREA (M) (M) (HAS) A. ROAD NO. 1A 1,940 7.32 1.420 B.20 SKID TRAILS 7,530 4.88 3.675 TOTAL 9,470 5.095 PERCENTAGE OF MAINROAD AND SKID TRAILS CONSTRUCTION = 2.51% LOG WINCHING

It is possible to envisage other layout patterns of roads and snigtracks/skid trails to achieve the same result of less than 10% damagefor the first embodiment of the method of this invention, and less than15% damage for the second, third and fourth embodiments of the inventionto the ground in the logging area.

To facilitate proper and adequate communications between the variouscategories of forestry operators, it is preferable that a reliablewireless telecommunication facility be provided. For example portabletwo ways radio with ear phones can be provided.

It will be appreciated that the roads and the tracks are constructedfollowing a pre-planned pattern layout to keep the damage to the earthas minimum as possible. This is achieved by the construction usingminimum length/area of jungle road/main road, snig tracks 98/skid trails68, and spur roads 58, as contrasted to the prior art methods, in whichabout 60% of the is jungle cover is destroyed.

Although, several embodiments of the invention have been disclosed inthe foregoing specification, it is understood by those skilled in theart that many modifications and other embodiments of the invention willcome to mind to which the invention pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is thus understood that the invention is not limited to the specificembodiments disclosed herein, and that many modifications and otherembodiments of the invention are intended to be included within thescope of the appended claims. Moreover, although specific terms areemployed herein, as well as in the claims, they are used in the genericand descriptive sense only, and not for the purposes of limiting thedescribed invention, nor the claims which follow.

I claim:
 1. A method of harvesting standing trees in a jungle comprisingthe steps of: constructing a main road across a pre-determined area of ajungle block comprised of a plurality of sub-blocks; constructing a spurroad leading from the main road to a log-landing area for at least oneof said sub-blocks, said at least one sub-block being bordered along atleast at one side thereof by at least a portion of the main road;radially extending a plurality of snig tracks from the log landing areaof said at least one sub-block; positioning a crane having an elongateboom structure within the jungle block and outside of said sub-block;using the boom of the crane to lift an operator up to the crown portionof a standing tree; the operator then cutting off the crown portion ofthe standing tree; securing a sling carried on the boom structure to thecrownless standing tree to be harvested; moving the operator away fromthe standing tree; cutting the crownless standing tree from its base andlifting the cut tree in a suspended manner with the sling and the boomstructure; and laying the cut crownless tree at the log landing area. 2.A method of harvesting standing trees in a jungle comprising the stepsof: constructing a main road across a pre-determined area of a jungleblock; extending, from the main road, a plurality of snig tracks spacedfrom one another; positioning a crane having an elongate boom structurewithin the jungle block; lifting an operator up to a crown portion of astanding tree, the standing tree being spaced from the crane, with theboom structure; the operator then cutting off the crown portion of thestanding tree; securing a sling carried on the boom structure to thecrownless standing tree to be harvested; moving the operator away fromthe standing tree; cutting the crownless standing tree from its base andlifting the cut tree in a suspended manner with the sling and the boomstructure; and laying the cut crownless tree on the ground.
 3. A methodof harvesting standing trees in a jungle comprising the steps of:constructing a main road across a predetermined area of a jungle blockcomprised of a plurality of sub-blocks; constructing a plurality ofspaced skid trails leading from the main road, wherein the distancebetween adjacent ones of the skid trails is in the range of from 200 to300 meters; positioning a crane having an elongate boom structureoutside of a predetermined one of said sub blocks; securing an alreadyharvested tree the harvested tree being positioned in said predeterminedsub-block and being spaced from the crane to a sledge, the sledgecomprising a bow and a spaced base portion, the base portion including acable hook, and at least one spike adapted to secure the harvested treeto the sledge; stabilizing the crane with a stabilizer member; securinga winching cable operably carried on the boom structure to the sledge;and snigging the harvested tree toward the crane at an inclined anglewith respect to the ground.
 4. The method of claim 3 further comprisingthe step of bringing the winching cable to the harvested tree bysecuring the winching cable to an auxiliary winch mounted on the craneand drawing the auxiliary winch cable about an obstacle spaced from thecrane.
 5. The method of claim 3, wherein the length of the boomstructure is of a length such that when the harvested tree is secured tothe winching cable at a distance of approximately 100 meters from thecrane, the harvested tree is held at an inclined angle of not less than5 degrees with respect to the ground.